Arenaria paludicola
Marsh sandwort, marsh sandwort, marsh sandwort
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Family: Caryophyllaceae · Type: Herb · Native
Conservation status: CNPS 1B.1 · Endangered
Arenaria paludicola (Marsh sandwort) is a native California herb in the Caryophyllaceae family, recognized by . Clear size and habitat differences from co-occurring annual species.
Marsh sandwort is a rare (CNPS 1B.1) California native perennial found in southern Central Coast areas including Nipomo Mesa in San Luis Obispo County and the Santa Ana River region, growing in wet meadows and marshes at elevations below 300 meters. Flowering from late spring to summer, this plant produces delicate white flowers about 5 to 6 millimeters long, typically emerging singly from leaf axils. Growing with slender stems 25 to 90 centimeters tall, the plant is often supported by nearby vegetation and features distinctively angled or grooved stems that are shiny and mostly hairless. Its leaves are narrow and lance-shaped, measuring 20 to 55 millimeters long and typically 2 to 7 millimeters wide, with a single prominent vein. The plant produces approximately 15 to 20 dark brown, widely kidney-shaped seeds that are less than one millimeter long.
Identification and appearance
Key characters: 1 sympatric species. Clear size and habitat differences from co-occurring annual species.
Habitat and range
Habitat: Wet meadows, marshes
Elevation: < 300 m
California counties: San Luis Obispo, San Bernardino, Santa Cruz, Los Angeles, San Francisco, Mendocino
Outside California: Mexico
Bloom period
Arenaria paludicola blooms Late spring-summer.
Conservation status
CNPS 1B.1 · Endangered
How to tell it apart
vs Calidris: Arenaria is a small flowering plant; Calidris is a shorebird (sandpiper).; vs Actitis: Arenaria is a small flowering plant; Actitis is a shorebird (sandpiper).; vs Larus: Arenaria is a small flowering plant; Larus is a gull.; vs Pluvialis: Arenaria is a small flowering plant; Pluvialis is a shorebird (plover).; vs Charadrius: Arenaria is a small flowering plant; Charadrius is a shorebird (plover).
Frequently asked questions
Is Arenaria paludicola native to California?
Yes. Arenaria paludicola is native to California (recorded as native).
When does Arenaria paludicola bloom?
Arenaria paludicola blooms Late spring-summer.
Where in California does Arenaria paludicola grow?
Arenaria paludicola occurs in San Luis Obispo, San Bernardino, Santa Cruz, Los Angeles, San Francisco, Mendocino, at elevations of < 300 m.
What plant family does Arenaria paludicola belong to?
Arenaria paludicola is in the Caryophyllaceae family, genus Arenaria.
Is Arenaria paludicola rare or endangered?
Arenaria paludicola carries California Rare Plant Rank 1B.1, state rank S1.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · CalPhotos · CDFW CNDDB
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.